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Mercedes S430 P0120 Fault: Idle Normal but No Acceleration - How to Fix?

Model: 05 S430 Mercedes Fault Code: P0120 Posted: 2015-10-20 19:38

Hello everyone, I've been troubleshooting this issue for several weeks with no success. My Mercedes S430 runs fine at idle when first started, but as soon as I press the gas pedal, it fails to accelerate at all. I've already checked and replaced the throttle position sensor (TPS), yet the problem persists. The OBD2 diagnostic code P0120 is showing up consistently. Anyone who has encountered this specific issue with a 2005 Mercedes S430—particularly related to the P0120 fault—please share your insights or troubleshooting steps. Any guidance on diagnosing or fixing the underlying cause would be greatly appreciated.

Related fault codes
P0120
Comments (1)
Anonymous 2015-10-21 06:14

Check the circuit for continuity and ensure proper grounding, especially around the throttle position sensor and related wiring harnesses. A faulty signal from the TPS circuit can trigger P0120 and cause acceleration failure even if the sensor itself is replaced.